Whoa… so I’ve been fooled. You can turn a mobile phone into a video projector with ease. You only need a single magnifying glass lens.
20170117/http://content.photojojo.com/diy/turn-your-phone-into-a-photo-projector-for-1/
- So that’s another use of the 4K smartphone screens, in addition to Google Cardboard VR.
Note that the article has links to more sophisticated projects too.
Gosh, now I have to reconsider… if you can do this many things with a smartphone, why do you even need the bigger computing devices?
Okay, never mind, no need to search for “orthographic projectors”… yeah, they do exist, just run an orthographic camera in reverse. But they are not quite as common.
- You don’t need to wait for 4K projectors to come on the market if you use a 4K smartphone as your 4K projector. You might even have luck making an 8K projection screen if you put together four 4K smartphones.
Yeah, so same photographic concepts here. On one hand, you could just try to use a pinhole aperture, but then you don’t get good light intensity. If you want depth-of-field, then yes you can use a lens, but otherwise that is the disadvantage. The advantage of course is that there is in fact greater light intensity focused. Bigger lenses better for this, of course.
- Good point! So, to explain the concepts easily. It’s like you just imagine a camera in reverse, and then you’ve got a projector. All the concepts of aperture, focus, and depth-of-field are the same. But exposure time is not, only immediate intensity measures matter in the case of projectors.
** Or wait, well, good idea. Long exposures to compensate for low-power projectors. Then again, bad idea if the exposures end up taking just too long.
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So now you’re asking. Is this really a good design? You have to build a projector housing for a smartphone. Well, if I had to make a call, I think it would actually work quite well for those who are into arts and crafts, well, you know, artists, so 3D scanning this way should work well!
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Well, and yeah, if you use two smartphones, then the projector can optically triangulate itself, or you can use that other technique. Oh yeah, and you’ve got networking too for app development.
Ha, funny way of putting it.
- Projector not working? Well you can turn your smartphone (or laptop or anything else) into a projector of your own.
Important! So, what are the merits of the smartphone projector system for 3D scanning? Well, let’s put it this way. The weakness is brightness and power consumption. Laser lines are brighter and consume less power, hence their optical systems are easier and cheaper to setup. On the other hand, incoherent light can work better with rough objects, and the lack of brightness can be better for 3D scanning faces.
So, in this, we also have to admit that projectors pose similar dangers to that of lasers. However, due to not being coherent light, the intense light does not travel nearly as far, so it is not as dangerous to use in outdoor environments, though for indoor environments and short distances, the tradeoffs are basically the same.